Development of nanocrystalline soft magnetic Ni-Fe-W alloy films and implementation into a microtransformer application

This thesis considers the development of the Ni-Fe-W alloy films based on the nanocrystalline size with good soft magnetic properties and implementation in a system. First, an electroplating process is developed for nanocrystalline Ni-Fe-W alloy films. Second, various parameters such as current density, content of the W, annealing treatment, substrate temperature effects are studied for improvement of soft magnetic properties. After optimizing these parameters, the plated 81Ni-16Fe-3W alloy films at a substrate temperature of 5°C and a current density of 5 mA/cm2 show the lowest coercivity and highest permeability with good electrical resistance. A Ni-Fe-W core transformer is fabricated in this study and characterized by the impedance analyzer.